SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a553b0f69fc6662eddf0f273795bf5c269deb291b5a79eb002d33a7d64932ac7' 
  AND token = 'xG/3XjIh+GwfbKz1Mb/6ZMiUh4arl7x629LW4RA/heM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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