SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '714835ee25ab930d37786a0fe233ec65087198bad0bcc10f1a9e3f1c0c8ede0e' 
  AND token = 'jbSZYpcwegn2CWWNUJ4JTBslHVothohU2i0N4h7wW40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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