SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '346218d3f63eb8db992a22967706973763710c58746308067c4cbc4cf170d71a' 
  AND token = 'Un26zZxJ75+romhhGGlnEIYFnikhbJ5sLqswTnaPUb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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