SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '842ef00f98faa95076b5ac31240de25391e8faa3a8a2f783fb8a01fdd59c7275' 
  AND token = 'Ss6qVmo6SI/3lZSii6Usmjgncc1XEqq+gIqhPJuA8Kg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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