SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af509aa99a967251a30c46259316e075e29cdcddb9554483794124b6e61c5d9d' 
  AND token = 'itg1/LFlqPVsq2iGv1h7VjkaDojKp5p5vFz57U6xFPE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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