SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f0b20e51a96eb1571d9b8bde19d5ffd1c74304517665dbae5057c7dbedaa9b8' 
  AND token = '1mgxmTgEfpgkwz43TXu+GJSe4g3pyZV0HmUtc7zm6Tw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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