SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '528508af9c0dc2ad6be178459606e21c70e919f9ec02a5d304186b155a594270' 
  AND token = 'eFX52LKPmqZwljikHVwwkHbXgJAFsSPw7Fpah6l2sK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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