SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3acfd426313c0800a02324f6acb4582a380d812f1967fb91e8d80191ef74e6b' 
  AND token = 'v0JiE++pNMSjzeLwx7hnYmNHKEUOUN2EU/tn6PuAL1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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