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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de248f275f9197692e2af038b99c2d50e21d6ad6a5e1f716f7d1a85dcad34a4f' 
  AND token = 'nQZnjR7xh2ZaeVXsOvk5SmjxlaM9ZTnNMsmW2w2/4XY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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