SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfe115a77ea82d68945ed45e454b58597a5df4820e380645dc4aff92893ee8d1' 
  AND token = 'rUQmEr/04xpDeMVB+YMzvcKUQZMk4x4BbcUwkHPLhHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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