SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '576fc07d6a79be23291a052ca5e4069963bc4afee8880a033d1e6625814f1f83' 
  AND token = 't6QZBI5an5ndVOwTSSosLrQuIwSUoUoDBOpI+dSud6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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