SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c55edcd7d8efe4042392fd277670da9742ffde2e3d964d4fae5e927255e17e6b' 
  AND token = 'QfSa/QdCDD06Xn7GRwxmBGhdVDX4llonLwKCqoprOzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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