SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03cc876fc944f3d8ecdabd38da4d5bfd7aeaf04cc438892b29cbad5ccb5a8918' 
  AND token = 'vcKJQvL7mUG7mTai0X9hJ/Nx+ahKnOUvEb61YCxgbCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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