SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '975065d6b1266704d1c9abc79a5385db1ffac559fb03e9f6255bbf53cd24e4b9' 
  AND token = 'eQ8O6iFbzASn9e/Udwmcrpz5LcUi9+cTMVpI4dDaBhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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