SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '977c117d5894f666a7be12979986900595357e88435a14de24ac763afc3a456f' 
  AND token = 'OLeYX+mHymqVAXoyV0nZYAYwH/ECtB49WB+nUlzMTrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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