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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfc4a437cece36fc1bc2a95ccac7879fc408175bf8279eb273b76cd242ad762d' 
  AND token = '9RSb7xuegkdk/dCoAr2EfaR1FuDF6H+bTw5BFx3XgbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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