SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc3f8fe7362f097be81e3f3ee78bd28f5f614beb1c6e7c15542dbf80e97d5386' 
  AND token = 'NjxJzmUokOfBeFFP+pcdKYLjDCt4RU/wLIUpdUmFQqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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