SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb8740d898d2f2982bc879511686a8e0afa75538fad7334841909aac3e47bd50' 
  AND token = 'KrDSrwesxYZ0t4RKAQZUzdlzAP/Akln9sgg/O0lYFJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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