SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87627dca2505a3968d7e404331322a476e9e111600eef9e4edb6413696766bff' 
  AND token = '0a/fFfOKq2HaLih12lchkMOpOiItTYUXOq3JC3MInOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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