SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '976b848abf51e89b327ef3c98d5a7fbb20c6afa69441371309eab494702a2703' 
  AND token = 'khJqMCBY8kGEkO7ksHXdJEUvjcKqBhwHcNB8tbrMB2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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