SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e52740a474a61de2602b673f815cfc906ab3df4680867c72db12564563693056' 
  AND token = 'wGXicQsYtor5eqSs1HMYp2szQpLaqTQV7UpyJbEnFBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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