SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1efc751afd47d7eb25c36a4b6e8cc47b1ec0c70724fd023263b9c24ce0361868' 
  AND token = 'dM3WQ3NlW+Nnlj7vpzfgTav7NGmYRmp4p+hg8ke4GwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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