SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dffb1755be6e9fe56f33f5730436b0ad6b7fd3e3138f273902437208f8b21167' 
  AND token = 'tWO/fBrTKAHuUJb34/HU1YqMw0FlqvxEk6VuQhhnmp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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