SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77e472a1eabe59bdff7f43d6e94338cdd57f1877a92ad05ace8260bc9a33386f' 
  AND token = 'Cj7TwGDgFaSZ6249aOtf4fOnijt71UdhmoZTPIL6Qd4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}