SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4867b6ee0c2320826620f3729c37c5b39857021043c29790346b09b443fba5cb' 
  AND token = '6TxvlLXMFO0D/ehYf/P6VGThdw11hOFJWdoHtjswHPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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