SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bce62ab609f00e683e1974a778a85273c2b8d40127e898a83ebe5fc10968605' 
  AND token = 'FOjjWOFILpuP5vrqWnK2pm5DhKyOguXErhdkpi0cM14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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