SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6468486bd0492c4891dcfcfdab501afdf3649d9e277a40ff607ffe2e4c8e6e3' 
  AND token = 'U3eD8aAMo32zGpq0smw75OMS0Mz6gk8UjhgfXepXLmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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