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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc9c6cc34ca2fa99c3ab90336569b44bd288b06db07251564acfbded1ae50f0f' 
  AND token = 'RyYQQdPN1nnFcRHbIzMIXj9QqM49NvD0M8p//mrqQyM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}