SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6743991fb86f704b304d084c8f293f3107b05d73e463df8137fdaa4696d9e85d' 
  AND token = 'gGJtAju/stcjSMA8WLDwbWWnxaa1qkUqu2U5uX7NUO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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