SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f4e1977bc86378b79c39d7e1ae2268b9e3686e0c5ba22fff9c9f9a7be294f13' 
  AND token = 'TkuzZ2ATaiz0YaG/Y+gw5qq8nr+ytz9K4Xbse/VHqS4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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