SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56b43c38c94c67f239cab0b826fe7f866cfc0f06d9c9a4369f28ae65968dd272' 
  AND token = 'KdTFYBoJ9JllCtZlgzF3OFRHXvv+/pJF4loojRkGgXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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