SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '137e39f1388c654777392939e0d94d4d3fc056ac8f4c25392d7e1a9f28ad51ba' 
  AND token = 'kXXy5n0+gqlYJDTAv/C0sQiGRN8aPkNzBpU8mwpenPk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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