SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ad214ec211b26f899976ab4cb78879dd1e687b65200fe8297559dade858dbc6' 
  AND token = 'QMS5FGwO8NhHW2POJ60VMkC41K3s6xUhrM+uwBRfTPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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