SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f15b72c61ddc3c62deb8fd0e364958d6966d5d122d6274ca56e2853ae8364db8' 
  AND token = 'q5Lp4YztL/zKlTWY+5DFOJZixzZCRgE7f4zJ+HJdjuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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