SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfcafcb530bfc8815c5af1392f264612f49e6a2f793396a135014f39f338892c' 
  AND token = 'imS6rZ3FgTIY7obDEa/SzKz97gOFsfVgiKWqID5zMFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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