SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc6501bf4a317710d3fe219482f20724dfb8ba21398a458c882f663e2713766b' 
  AND token = 'Hj6yIUCjxfSNYf5RJzNgfIG8ILQvwVa4qeXfw8b2L2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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