SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b10eda9e541b94922d20f7e5a67b7c185741d0aa8f15c2a83743139b98065cd' 
  AND token = 'zLztV6Ujy4HoLG+tBJE92GFGMwLyC15RjGlUUwpBFaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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