SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a29b482752aa2682dfb2c2083765f6c18b0d90294064b866fb9dafde164a5758' 
  AND token = '/qXxZyTqiaxs8OFX293LP0flvzFiMxoDUnNKlWuQVWU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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