SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eabc832a108df2b0a96edfc659953234642fb1ec8609c3f0ffc334e898488038' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.01857

JSON explain

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