SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a3cc8e5b123f551a4632051af1bdd3dc9ea69fb08d8f36c9a1af78ab67419bb' 
  AND token = 'wJjg/JKh8/dd2rOy3042HAuwap+rBYu+ns+ljupz510=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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