SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4492618d14888caba7f06dac6d42b301ff886ef6764625da207117247dc82da2' 
  AND token = 'J7i5gacF0hxttbwf7dNIcgv76hV+fiN3tbcLK+lBhCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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