SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c313ea772565d4826cc8623029c3d595c230e495c91f317b6455af667af694fb' 
  AND token = 'vB7f1oTMepZde+b04SkYPB/olePBvhtLh8amltp7LzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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