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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cde644871aa483e1cc449c702d5168c1b722d99b583f7cb5c27b3dd0f347f9c' 
  AND token = 'sEh/42Zrriiwr+Ji9HCrlC2yuzd/6Y4/537mb7XIWjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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