SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac6a3bc5961e4e991f26a1cb8a6ddbc71c255739835b71725eaeb76e353c63be' 
  AND token = '7iwfENg7txa2iBEnA1I3VJ4U6NK21LGzXrvpKvcgLP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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