SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6948b273dd4e18ac94d467c5dd377e8350758b49b1b1d3f00bedbf439c69b0e1' 
  AND token = '3ehvCXgpLjpRae7pm1lfnmWS06eIo1rhlzuYDWoQ8b0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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