SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f9f4dec85152af00c7e20606233e483c701b2b8293fd645b2d336907daf04f6' 
  AND token = 'RlWLtjr5O+c4JF/ol718k5aJu5I5bEgQwqzyTGAYFjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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