SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '18c1365653382f5e239413714ab00563d7d3867abc74cdb26f176e7e308a2798' 
  AND token = 'iIowSxZy5irtgDyMJZ+CywiSswSji5gFgPsnRJSOtFs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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