SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '0ab681d0835e64914ad885273f0efcafc5c0a3ae547d690bb1240e96863a2b74' 
  AND token = 'nIcj6isRqp1FQ5zgcG5FxldamIHVxtlJBJitCynzakY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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