SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbc0fd842f70175cd8994552a466c375cb50b3dc4a3ddaaeaa8263307464efcc' 
  AND token = 'Dz+3wJwvkk6bu9yvAOLZDHLiMHYHiKJAA5AoZnZzBi8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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