SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '458b991035915c79a3d866ca8453e2da0548429733a2ce42076ff3fc31c6c48b' 
  AND token = 'uc8vyFKqW14ErkFBi/vcYcuoKJRMZta3rH17bDYpu94=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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