SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51bf790bc09a8768e6aba3a0f489fd314a956a48262fdb3b635b3ed6c928f243' 
  AND token = 'LVbA0nLYZEhW/uI6+L2iat1RJXFg2xnqvyPB3TkVMgQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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