SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7f4c25c01bea673d22b4e22e70b8e2aa0f3289e5249ee179e07cbbb22783b72' 
  AND token = 'K75gemxnnDRquELscXB4kTgCGcqsvD4hCPSsayZxois=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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