SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '323cc3cdd7f41ffddf4db8824d06ebd918aec4378cbf6a28948e4cb8296be835' 
  AND token = 'nBJd9yTPoGTRVDrWrOqwAQsgi/Zf+ijpJ3zg53MfkHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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