SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '50b075076cee3c77bb52d82891ffbfb9676963108cea4768550a0725cfeafe8a' 
  AND token = 'roHsUI40yq+w/zWv0mBfGp7nkLtGLydDLvZNcVaMTjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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