SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ce277808e5860b925f38334ebf38a9c208b942d2eeb0255f45a1d3466e81948' 
  AND token = 'MHyHw8jPHnBM2kPRz07ozBGOA+hbJHDYV1KxKNa6JzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00073

JSON explain

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