SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '206b4c7d12fbee556b36ede3b2845519272a6798ea2ad58453e06c95f5336ecc' 
  AND token = '90nUfVzLWdsolcSN8EvGet8PC+PGkmDilLeCP76MvwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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