SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4256b3d2119a4052b734a3a473f0bf7fa6e35de77710534d2e16b27d15a45cd' 
  AND token = 'ubEr8XLPC+pbhEZFc/w5YNGshlu6z/ngxptYe9OzVyE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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