SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b08115f0b57f61e51b531bd2d43535b2c13bb787145b89cf94f4e80ba52ac782' 
  AND token = 'PGt3qsKZ1JZy358fDStQe2Dkxh9pFgS8Qdhfb4RpcQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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