SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3246c20bc3f427647d6718f5020ffe7369826401c209c8221778a25d3948b9e1' 
  AND token = 'FR7X2WYv55R36aXvQ0+VHE4mSRXgmThppCD3K8t3uQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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