SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffc6b1fc3fc1e0a86db545e3027852a7bcf0e8961120d6cdd586f0d885b96f12' 
  AND token = 'is5nCET+EwcPUuJQGwmfqwLhWj23lXnzQAefe4fCNlY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}