SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '540f1361c485580db8786e3e6ab0419e4923b45d8cb9fce0a6366b0af16ea6a9' 
  AND token = 'kdGrbCNXaoUFg2bid9PeOn+ldSetOjPr7GIIzkka5fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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