SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0f3739bfbd819c20525f64fff1c77ff40fafa3c72302a462117fd50d92ccc0b' 
  AND token = 'YKbWtiXWVGrfm4zuGXcvVq7ZXJOIuwdWIpN/vcBSm8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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