SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19529039fe22a8cb4a942e9c8dfb646e17a786637a1936c6558d82e3c4686892' 
  AND token = 'ogulfuEgT9ldBM5z9EaoxDifBZwFcxgTSIcL8IJGsWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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