SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc49e54dde02a60094333b8f39a8242ecc59ebb13092a5a1e570f842995c6957' 
  AND token = 'JLf4qK4/ACmqTSMXUJuXfUCwWVQ+3hJTB6sPNgjbsu4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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