SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e17ba66934a82daa10df35903600297d856fc0c1b66208687923053a26bc6b17' 
  AND token = 'PUsQ93GxjpUces+LS2DHsOmgflRefWF5oMcYvDDTbZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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