SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f87120a928fb300382099998847ac965bb086910bfb3ed873bd1c4482f54339c' 
  AND token = 'i1US0XMdv8llHaiblvTgamWgBnpPNefDujc3F3tt8qM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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