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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb9e6e7ddde3c288a85aac3fee0248ad97b07708c1bd5172a4b198e0972b8824' 
  AND token = '5VbEsiIQhIKWbKRIf1EJtVYpVxBlJAZF0nuHWpZtV64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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