SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6246fbf47b91496c2a221d3ad6dc3eee1021f48a503c087c8130332f3ce6d86' 
  AND token = 'XvsVqCI/wspDZF6awEpjITlyy+iU7xcxsehKaloGKN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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