SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81d1cb356faecd83ef8f32a47c0591f488489569253bf6b0a47c40de154db5f4' 
  AND token = 'yBUHG2tFPsnMqQ9qveYASJOX8z+N2zCQBfaVXjB/bME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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