SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '835d806725662de86bf93b36bf54df5ad5aa46f0762e1126151af734d5f566e1' 
  AND token = 'JBPYy1vfFNJY7H6OPTJUXmsS+A96qncswZbwZLaOgFA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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