SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2cf1f82949f96989cbb58a0afdd3307a47f72531a4462e56178dfe1ecc56b36' 
  AND token = 'C+h0Zkx0aJMpbASrElqZkvpE+GJHBl7xNAsY8Lpip78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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