SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81cf60755b84e672741001da25c37abe9c4cd2d4a21e22002aef9f2cb50a7c6c' 
  AND token = 'HXB+iYFxouyHXJqBvFTY4NkCAbrrGwAMkGwIKWWllJ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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