SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '338a9c83ecdcfb52f9907e8ad59347ec5ce5dde9a2ed25915509288dd95d2d0b' 
  AND token = '7N6efwo+cj496tPAwS8NykzClfX3RW+wz8rRt0NHN28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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