SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfbc1a655c4285b747cddad87d5bc3f5f65c08078bf1de5cb888e3bdc8b242dd' 
  AND token = 'FUFn0A1R9u3GfA/wGMbGbasGMKZcWDSsfTEnqzf8Z5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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