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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a51a3e9b809155eb5ea0f9f28aaf5da6064fbd114a1c1ed048a8e984c3ee9d4d' 
  AND token = 'HUX9+yvHlSfw3BohnNPT33NZb0ivndu6n4oUrm/qf40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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