SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd1978b2ed37da44dd6ecd240d245d5d9e1804aabd90e9e8a4c7aa837de7ffb69' 
  AND token = 'brwdmhDHjael4ElU8qkrRVOkaX2ck6bdsHjLX5uhCPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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