SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '474d496ffe202c435931db7cbee3edd002163029cb212f8ad7fa6006d87d4dc3' 
  AND token = 'eCRK/TniCaWsstBE6bwv/oJtZipyfjq8KEF+Bq/2xMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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