SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fcfe397cc1119a1874693de6237748694bb497034d99c50010b54409ec9495e' 
  AND token = 'mrlvcV7wH6iM7splqrtY1r5AThPrbuvRaNte3rxm7U0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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