SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb40c390e4cd99e7c329d6057c62ade22bcb4d15f9602a19140009a537d8735c' 
  AND token = 'ByJactzm3kym+/AMc8ZyXPCf+lteId/4zpgUuj25+xs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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