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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3e34979ab899a3537850bd7d1a2763ceace52cdd41a8d0387f4b7173c080f90' 
  AND token = 'NkTg7nEcpPQep/EdoCE/QyusSvJhzDDIq+pYQRE6Bso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00061

JSON explain

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