SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f274bfeabb1e8c550fb726fa67c16b16395f3ccedcd5edfe479690916cc03dff' 
  AND token = '3mwa3GeJujgzoA/7OsPy0PC4Ke7yygtfh5uioXGE7l0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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