SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd6423463e951c7aba3e1d040e300ba20983eef1565f037893213344bd73e158' 
  AND token = 'ZCQwq+MvBc+w4I5noPzBpipMJvGLAC7C+TmSdxlZebg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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