SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5bdd73991ef6804af191c54e3f0014456846a83dd49d0b2083e73546914b1b8' 
  AND token = 'hMDxuUhjFY2/xGXAyHAh61j8PFbgWR2EsEbLzYdv/fQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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