SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54ec9d774be18fae7f78c2d38d421a7a62221156c6cda5f83e9b240d23ca6064' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00110

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}