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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29a90a46b9d7e6113199491051df9e6f64eb7fe6caba775eda0e4e9a5e1142f7' 
  AND token = 'li52tTTSyYdVJpfzPMspe0WJjOoV8seVShs0g3TGnQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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