SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71ac07015b263a8f66055a8bc21b718bf73f8048f8fdb2a652ffdcd42f124059' 
  AND token = 'dxucVH4XzBYvE68BGJtkJelQ1r+RK/1huqMt0W0IMfY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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