SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56cf14b0310d549017b438ec231bafac5506956ac44a5d08e1309b4113c995d2' 
  AND token = 'EDglbqVkc34i49SJ4uj2EEUzFfoQHB6+jvNhho1+XHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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