SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '7f3f7195d0f38020bb5914b553b7101853effeadc77c7ad633360198891fde43' 
  AND token = 'IQnn72/ust/GpzgnLvYsUKh3MCGnz+5sNbpK9gP8RYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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