SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b90938f624c61d61f10a82af3ad6f2acb82660fca83902c1408d9ef11be35791' 
  AND token = 'W7Y09R/0agRhq5OFahj0brh9nAJT0NhRdQcvLzNoB70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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