SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f921a645f1d56798931e49f3407b2e6caa4a7f45fd064ddf1c13a1c55269eb4' 
  AND token = 'EKxf82ASOcz8kDtMTaLjWOgaxKQkdYP48Mm+KHCTs64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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