SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '826227f1516f4ba3c06df048f308ca8d3165c70e9bd591046674d50eea9c8869' 
  AND token = '0RQE+JIMoZPhGY4COjGlN/yVv2QaKh6WiAMfBr6b5O0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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