SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78433b66adfbd29f70a1721872536e03c5fb72f5403ac6bb1ba8ff08b4cafeca' 
  AND token = 'x+L9zSIgWwn/EfM4YcI06aDIvmLuwOIK2vLeI+BBuvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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