SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd50655f33c077fd079f26c4b3b514a9d8300138e9391133e7be0f13a8979a6a5' 
  AND token = '7zzDEaZS//1BJlyn+zDP0CvJjYSGnUo7kujruhn/aHA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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