SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a4d637f8f3980daf8d8175dc5e600426576142238c987173d3c1fab9183a7aa' 
  AND token = 'bHvqCKqg1r93rIBvZNhlocTYxUC1lAfTg4oK7SXQG38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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