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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a4bbca752ce6701bb38f06da8dc3eef2c2eea616aa2f1a5fdb8f62187c1c7094' 
  AND token = 'H/2saClZ4ZV9rvkZZfceWrUS7S+XmOEc+45qQ+kHqXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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