SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0ccc54b0929aac21cecb5cd00dd09cba5264d923b7923589798e068c006a2ea' 
  AND token = 'GVJWdgUjCK1ZFfAS0vWuqoFw7iN7Mb8oy/nwCvIWuXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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