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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6f9598e3fbc89efad4b82b1ad83427d6c0f3a2d8986703729b874b65a516786' 
  AND token = 'lj8EZEIvO6SzR68u1p9Z7mdGXEsjOxQn70NwsIr3sQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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