SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c89256dcebb86440eb2c2832b8a4ed95e15989b1fc118540024a2bad42059212' 
  AND token = 'zPco0uRG+rzh/ZzzylN+omziGfU52E0zTD1HzSOVuR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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